In the aviation fueling industry, hydrant valves are installed in pit boxes below ground level and function both as a connection device and an on/off valve in the underground aviation fuel distribution system. A hydrant coupler is the other half of the connection system and controls fuel flow and fueling pressure during an aircraft refueling operation. In a typical connection system, the interface between the hydrant valve and the hydrant coupler is manually opened by the fueling operator using a handle on the hydrant coupler. When the hydrant coupler is opened, a face seal in the coupler engages a hydrant valve adapter to form a secure fuel flow path from the underground fuel pipes through the hydrant valve/coupler and into the aircraft.
To meet industry requirements, a secure latching mechanism is used to ensure that the hydrant coupler remains attached to the hydrant valve under an fueling pressures and flow. In one design, the latching mechanism utilizes an external actuating collar that drops in place under the force of gravity or a spring force to automatically latch the hydrant coupler to the hydrant valve. To disconnect the hydrant coupler, the fueling operator lifts the actuating collar to release the latching components. This type of actuating collar design presents a fuel leak risk should the interface seal fail during engagement and/or fuel flow. An interface seal failure would allow pressurized fuel leakage that may be sufficient to lift the collar and disengage the coupler. This disengagement may cause the hydrant valve poppet to quickly close and, in turn, create relatively high surge pressures within the hydrant valve sufficient to cause, among other things, a fuel spill.
To avoid fuel spills, hydrant couplers must be equipped with a lock mechanism that maintains the actuating collar in the connected position during connection and fueling. Existing collar lock designs place the collar lock on an external portion of the coupler. The fueling operator has to manually deactivate the lock in the process of lifting the actuating collar to disconnect the coupler.
To improve fueling ergonomics, fueling operators may use robotic connection devices to connect the hydrant coupler to the hydrant valve. These devices lessen the manual labor required to transport the hydrant coupler and fueling hose to the hydrant valve. Robotic connection devices are often incompatible with externally mounted actuating color locking mechanisms. As a result, fueling operators sometimes deactivate or remove the external collar locking device to enable robotic connection.